I posted this in my other thread, but by the title you'd never know it. So I'm re-posting it here. Also, i think there are different water suppliers for San Jose. My landlord pays for the water, so I have no idea which one I have. I'm in postal code 95123, if that helps.

It appears San Jose gets it water from four different sources, according to the helpful map on page 2 of that PDF. I happen to live in a "groundwater" area. We have crazy-hard water. Average 415 ppm total dissolved solids. I don't know if that's a good thing or a bad thing for AG brewing.

According to this page via Google search, I should be comparing "Hardness as CaCO3" to "Alkalinity as CaCO3" to determine whether I need to add stuff to the water when attempting certain types of beer. My water report only shows "Hardness as CaCO3." I don't understand! (flails arms above head)

Are there any other San Jose brewers here who could help me interpret the water report? Basically, should I be doing anything to my water to get better results from my AG brewing?

I know I'm basically asking somebody to do my math homework for me , but I'm hoping that, if answered, this thread can stick around and appear in search results for other San Jose beginners looking for water advice.

(and BTW, the OP is talking about a section of the city that gets their water from "imported surface water", so their results would be different from the "groundwater" section) (not to mention those who live in "mountain surface water" and "imported surface water including hetch hetchy") (more flailing)

To put everything into perspective, keep in mind that when it comes to all grain brewing water is important in order to mash at the right pH levels (between 5.1 and 5.4 measured at mash temperature, slightly higher if measured at room temperature)

Ok.. so hardness is important to have for mashing and fermentation... hardness is determined by minerals like Calcium, Magnesium, etc.

You want to be in the 50 - 150 ppm for Calcium and 10-30 for magnesium... but not necessarily...

These minerals bring the pH of your mash down, and that's good when you are brewing light beers...

When you are brewing dark beers, the acidity of the dark toasted malts bring the pH down as well, and if you couple that with the minerals that cause hardness, then your pH may be too low (below 5.1) during the mash and your starch to sugar conversion may not be as efficient...

So that's one aspect...

You then have to take into account the alkalinity of the water... Alkalinity comes from your carbonates (i.e. bicarbonate)... these ions raise the pH of the mash...

Alkalinity in this case is bad for your light beers, but good for dark beers because it balances the acidity of dark malts, you follow?

So, what you need to do is... Since your water report doesn't list Alkalinity as CaCO3, you're going to have to call the city's water department and ask to speak with one of the engineers and get that number...

Since you don't have it, I'll use the example above... they have listed:
Total Hardness, CaCO3 124
Total Alkalinity, CaCO3 79

Here's what these two numbers together mean... this water is probably good for your mid-range beers and some darker ones... neutral pH of water is 7... according to the guy above the pH of his water is 7.8... (pH of the water itself doesn't matter as much as the pH of the mash when the grains have been soaking in water for at least 15 minutes)

If you were to try to brew a light beer with this water, the alkalinity will probably make the pH of your mash be too high... you could try simply adding Calcium Sulfate or Calcium chloride to make the calcium bring the pH down... 1 to 1.5 tsp is way more than enough, prob .5 tsp is all you need... however, if that doesn't bring the pH down to where you need it, then you'll have to get rid of the alkalinity somehow...

One way to get rid of alkalinity is to boil, and the way alkalinity is removed when boiling is by combining with minerals like calcium to form calcium carbonate (a.k.a. Chalk)...

... and that's what I meant by comparing hardness as CaCO3 and alkalinity as CaCO3... if your hardness as CaCO3 (meaning calcium, magnesium, etc.) is higher than your Alkalinity as CaCO3 (meaning your carbonates), then you can pretty much get rid of all your carbonates since there is enough minerals to form chalk and still have some leftover for your brew (cause remember you need at least 50 ppm of calcium)... that's good if you want to brew light beers...

If on the other hand your Alkalinity as CaCO3 were to be higher than your Hardness as CaCO3, then you will have 'residual alkalinity' because there is not enough minerals like calcium to form chalk...

that's one issue... the second issue is that you will use up most of your calcium trying to get rid of alkalinity and you need at least 50 ppm of calcium to have a healthy mash and fermentation... that's not good for light beers...

In this case, to reduce all the alkalinity you may need to add more calcium to the water, treat it with slaked lime or lactic acid, dilute it with distilled water or just stick to brewing darker beers...

So that why you really need to get Alkalinity as CaCO3 from your city's water department... so you know if you can get rid of alkalinity by boiling your water...

Whether you want to get rid of alkalinity or not depends on the beer you are brewing... for light colored beers, absolutely... for dark colored beers you probably don't want to get rid of it unless you have too much... and if you don't have enough, you may even need to add a little bit of alkalinity...

I hope that makes more sense...

PS... Alkalinity is sometimes give in the form of HCO3 (a.k.a. bicarbonates)... if that's the case then Divide HCO3 by 61 ad multiply by 50 to get Alkalinity as CaCO3

Oh my goodness, thank you so much for that great & detailed explanation! I'm embarrassed to say it has taken nearly a year to get back to you, but I really appreciate your post. Thank you! I hope others were able to glean some helpful info from it in the mean time. Three cheers for BeerJorge!

More news ... the San Jose Water Company finally coughed up the numbers that were missing from the online water quality report.

Keep in mind, these numbers apply only to the north-central area of San Jose -- the section that gets its water from "groundwater" sources (the yellow area/column in the San Jose Water Report). Check out the map in that PDF to make sure your water comes from this area. Most of the city (green) gets its water from "Imported surface water" and a small portion (brown) gets it from "Mountain surface water."

Incidentally, the Gordon Biersch brewery is just a few blocks away. I pinged them to see if they would also share their water report numbers, for comparison. I'll add them here if I hear back.

At least that's a starting point for ballpark expectations of what the water may need. It sounds like the actual chemistry will make itself known during mash-time calculations. There's quite a range for each of those values, eh? So be ready for anything.

Yay, excited about finally being able to monkey with water chemistry (another rat-hole ... I like beer-related rat-holes ...)

Another SJ brewer here, with groundwater. Frustrated over the lack of detail in our water report, I've resorted to using RO water for mashing. Our water sucks anyway, but now I'll study your findings and see if the water is useable now!

In general if you only have a 'total hardness as CaCO3' number you can assume that your alkalinity will be somewhat less than this with how much depending on how much chloride, sulfate and sodium the water contains. From your reported value the average total hardness value is 323 ppm as CaCO3 and the alkalinity is indeed somewhat less than this at 280 ppm as CaCO3.

As for comparing hardness and alkalinity to determine whether water treatment is required: it isn't quite so simple as that. Alkalinity is a measure of how much your water resists the malt acid's efforts to lower mash pH into the right range. Calcium reacts with malt to supply acid. Kolbach's residual alkalinity (RA) was a stab at how much of the water's alkalinity is left over after the calcium/malt-phosphate reaction's acid has neutralized as much of the alkalinity as it can. Thus calcium does have a mash pH lowering effect. RA has been widely overused as a water/mash design parameter and, in my (relatively) youthful naivite I advocated doing that. The approach we take now is to measure or estimate the amount of acid required to move the base malt to desired mash pH, the amount of acid supplied by high kilned malts and the amount of acid we estimate is released by the calcium/malt reaction. This last is based on Kohlbach's observation that 1 mEq of calcium produces 1/3.5 mEq of acid. Because of this 3.5 ratio calcium isn't that important in most cases (shift pH by perhaps 0.1) but alkalinity always is.

A couple of other comments:

Calcium hardness must be 3.5 times greater than alkalinity in order to reduce RA to 0.

If Calcium hardness is greater than 3.5 times alkalinity RA will be a negative number

You do not need 50 ppm calcium to brew good beer. Think of the Bohemian Pilsners.

Alkalinity should never be expressed 'as bicarbonate'. What's worse is what one of the spreadsheets does: saying that alkalinity IS bicarbonate. IOW if you add lime to RO/DI water the bicarbonate ion field lights up with a finite value even though there is NO bicarbonate. The 'as calcium carbonate' is confusing enough to the brewer but the 'as' tells a chemist what is going on and there is precedence (based on the way natural water dissolves limestone) in the US water treatment industry for this practice.